P0320 Code: Causes, Symptoms, Diagnosis & How to Fix It
P0320 means “Ignition/Distributor Engine Speed Input Circuit.” It is a generic OBD2 powertrain trouble code indicating an electrical problem with the circuit used by the PCM to receive engine-speed or ignition reference information.
Depending on the vehicle, this information may come from the crankshaft position sensor (CKP), camshaft position sensor (CMP), distributor pickup, ignition reference circuit, or another engine-speed sensor. The exact system varies by manufacturer.
The PCM uses engine-speed information for important functions including ignition timing, fuel control, and engine operation. If the PCM receives an incorrect signal or loses the expected signal, it may store P0320.
P0320 Code Symptoms
Possible symptoms of P0320 include:
Check Engine Light
Engine cranks but does not start
Hard starting
Engine stalling
Engine misfire
Hesitation
Rough running
Reduced engine power
Intermittent loss of engine operation
Some vehicles may only illuminate the Check Engine Light, while others may experience severe starting or drivability problems.
Common Causes of P0320
Several problems can trigger P0320.
1. Faulty Crankshaft Position Sensor
A failing CKP sensor may provide an incorrect or intermittent engine-speed signal to the PCM.
2. Faulty Camshaft Position Sensor
On some vehicles, the CMP signal is part of the engine-speed or ignition reference system monitored when P0320 is set.
3. Damaged Wiring
Broken, chafed, burned, or shorted wiring can interrupt the sensor signal or power supply.
4. Poor Electrical Connection
Loose terminals, corrosion, water intrusion, or damaged connectors can cause an intermittent signal.
5. Ignition or Distributor Problem
Older vehicles may use an ignition pickup, distributor sensor, or related ignition reference circuit instead of the sensor arrangement found on newer vehicles.
6. Open Power or Ground Circuit
An open power or ground circuit can prevent the engine-speed sensor from operating correctly.
7. Short Circuit
A short to ground, voltage, or another circuit can distort the signal received by the PCM.
8. Damaged Timing Components
Although P0320 is primarily an electrical code, mechanical problems affecting crankshaft or camshaft reference signals can sometimes contribute to related symptoms.
9. PCM Problem
A failed PCM is possible but is generally considered less common than sensor, wiring, or connector problems.
Why Engine Speed Input Is Important
The PCM needs accurate information about how fast the engine is rotating and where the crankshaft and camshaft are positioned.
The crankshaft position sensor typically provides crankshaft position or timing information that the PCM can use to determine engine RPM. The camshaft position sensor provides additional information about camshaft timing or position.
If this information becomes unreliable, the PCM may not be able to control ignition and fuel delivery correctly.
That is why a P0320 problem can sometimes result in an engine that cranks but does not start, rather than simply causing a Check Engine Light.
How to Diagnose P0320
Because the exact engine-speed circuit differs between vehicles, always use the correct wiring diagram and manufacturer specifications.
Step 1: Scan for All Trouble Codes
Connect an OBD2 scanner and retrieve all stored and pending codes.
Look for related codes involving:
Crankshaft position
Camshaft position
Ignition
Misfire
Engine speed
Communication
Power supply
Additional codes may help identify which circuit is causing the problem.
Step 2: Check Freeze-Frame Data
Record the engine RPM, coolant temperature, vehicle speed, and other available freeze-frame information.
This can help determine when the fault occurred.
Step 3: Check Technical Service Bulletins
Search for manufacturer technical service bulletins for the specific vehicle.
Some vehicles may have known issues involving engine-speed sensors, wiring, connectors, or ignition components.
Step 4: Identify the Engine-Speed Sensor
Determine which component provides the relevant engine-speed input.
Depending on the vehicle, it may be:
Crankshaft position sensor
Camshaft position sensor
Distributor pickup
Ignition reference circuit
Another engine-speed sensor
Do not replace a sensor until the vehicle-specific system has been identified.
Step 5: Inspect Wiring and Connectors
Inspect the sensor harness carefully.
Look for:
Broken wires
Chafing
Melted insulation
Burn marks
Corrosion
Loose terminals
Bent connector pins
Water intrusion
Repair confirmed wiring problems before replacing the sensor.
Step 6: Check Power and Ground
Use a wiring diagram to identify the correct power and ground circuits.
Test the circuits according to manufacturer specifications using a digital multimeter.
Do not assume that every vehicle uses the same voltage or resistance values.
Step 7: Test the Sensor Signal
The correct testing procedure depends on whether the vehicle uses a Hall-effect sensor, magnetic pickup, distributor pickup, or another design.
Use the manufacturer's specifications to check the sensor's resistance, voltage, signal output, or waveform as applicable.
Step 8: Monitor Engine RPM While Cranking
Use an advanced scan tool to monitor engine RPM while the engine is being cranked.
If the PCM does not detect the expected RPM signal, the crankshaft position sensor, wiring, power supply, ground, or related circuit should be investigated.
Step 9: Check Related Ignition Components
On vehicles using a distributor or ignition reference system, inspect the relevant ignition components and connections.
A problem in the ignition reference circuit can prevent the PCM from receiving the engine-speed information it needs.
Step 10: Clear Codes and Retest
After completing the repair, clear the stored codes and start the vehicle.
Perform a road test and confirm that P0320 does not return.
How to Fix P0320
The appropriate repair depends on the confirmed cause. Possible repairs include:
Replace a faulty crankshaft position sensor
Replace a faulty camshaft position sensor
Repair damaged sensor wiring
Repair loose or corroded connectors
Repair an open power circuit
Repair an open ground circuit
Repair a shorted signal circuit
Repair distributor or ignition reference components
Correct damaged wiring caused by heat or friction
Perform required sensor calibration or relearn
Repair or reprogram the PCM when testing confirms a module problem
Do not automatically replace the crankshaft sensor simply because P0320 is stored. Testing the circuit and identifying the actual source of the missing or incorrect signal can prevent unnecessary parts replacement.
Is P0320 Serious? Can You Drive With It?
P0320 can be serious because the engine-speed signal is important for starting and normal engine operation.
If the vehicle cranks but will not start, stalls repeatedly, or has severe hesitation or loss of power, it should not be driven until the problem is diagnosed.
If the vehicle starts and operates normally with only a steady Check Engine Light, a short trip to a repair facility may be possible.
However, intermittent engine-speed sensor problems can cause unexpected stalling, so prompt diagnosis is recommended.
P0320 vs P0335
P0320 indicates a problem with the ignition/distributor engine-speed input circuit.
P0335 generally indicates a Crankshaft Position Sensor A Circuit Malfunction.
The codes can overlap in the systems they involve, but P0320 is broader and may apply to different engine-speed input designs depending on the vehicle.
P0320 vs P0340
P0320 concerns the engine-speed/ignition reference input circuit.
P0340 generally indicates a Camshaft Position Sensor Circuit Malfunction.
If both codes appear together, inspect the related camshaft and crankshaft sensor circuits, shared power or ground supplies, wiring, and connectors.
P0320 vs P0300
P0320 indicates an engine-speed input circuit problem.
P0300 means Random/Multiple Cylinder Misfire Detected.
A faulty engine-speed signal can contribute to rough running or misfire-like symptoms, but P0320 itself does not confirm that the engine has a combustion misfire.
Frequently Asked Questions
What does P0320 mean?
P0320 means Ignition/Distributor Engine Speed Input Circuit. It indicates an electrical problem involving the engine-speed or ignition reference signal received by the PCM.
Can a bad crankshaft sensor cause P0320?
Yes. A faulty crankshaft position sensor or its wiring can prevent the PCM from receiving a reliable engine-speed signal.
Can P0320 cause a no-start?
Yes. Depending on the vehicle and the underlying fault, loss of the engine-speed signal can result in an engine that cranks but does not start.
Can P0320 cause stalling?
Yes. An intermittent loss of the engine-speed signal can cause the engine to stall or hesitate.
Is P0320 the same as a crankshaft sensor code?
Not always. P0320 is a broader engine-speed/ignition input code. The specific component involved depends on the vehicle's design and manufacturer.
Can I drive with P0320?
If the vehicle has stalling, hard starting, severe hesitation, or loss of power, avoid driving it. If it runs normally with only a steady Check Engine Light, a short trip for diagnosis may be possible, but the problem should still be addressed promptly.
